Mec 113 Pdf

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Mec - Download as PDF File .pdf), Text File .txt) or read online. TECHNICAL DRAWING (MEC ) Mec Basic Workshop Technology 1. MEC Course Background/Summary: Ball bearings are rotational components that contribute to the high performance and lifetime of mechanical. 2. MEC Materials and Processes of Industry. 3. ELE A.C. and D.C. Circuit Fundamentals. 4. ELE Programmable Controllers Offered Fall Only. 3.

It provides a protective non-oxidising or reducing gas shield smoke-like gas around the arc to keep oxygen and nitrogen in the air away from the molten metal. It increases the rate of melting i. It enables the use of alternating current.

Additions to the coating can be made during manufacture which will replace any alloying constituents of the core wire or the parent metal which are likely to be lost during the welding process. It gives good penetration. It increases or decreases the fluidity of the slag for special purposes.

It can, for example, reduce the fluidity of electrodes used for overhead welding. AND D. The engine-driven generator-set can operate quite independently of any electrical supply, and for this reason is used on site work where no mains supply of electricity is available. The motor-driven type of generator-set is chiefly used for the type of welding work performed inside a workshop, and is therefore often permanently mounted on the floor, but the portable type of set is' also available.

The electric motor provides a good, constant speeddrive for the generator, ant: is not affected by the load imposed upon it. Transformers The a. See Fig. The a.

Transformer as its name implies is an instrument which transforms or steps down the voltage of the normal mains electrical supply to a voltage suitable for welding, i. Unlike the d. Generator the a.

Transformer has no moving parts and for this reason is usually referred to as a static plant. The advantages claimed for the a. Low initial cost.


No moving parts, therefore negligible maintenance. Higher electrical efficiency. Easy to transport. The disadvantages are few but important Coated electrodes must always be used. Voltage higher than in d. Welding of non-ferrous materials more difficult than with d. Electric Welding Equipment 1. Generator or an a. A properly designed electrode-holder Fig. Two lengths of flexible cable to carry the current to and from the One cable runs from the welding plant to the electrode holder; the other from the plant to the work bench known as the ground cable.

A wide selection of different-gauge electrodes of various materials. A head shield or face screen fitted with special coloured lenses as recommended in B.

See Figs. Note An electric arc produces a brilliant light and gives off ultra-violet and infra-red rays which are very dangerous to the eyes and skin, therefore never attempt to look at the arc with the naked eye. The helmet type of head shield fits over the head, and leaves both The face screen provides adequate protection, but needs holding by hand.

A leather apron and a pair of gloves. A welding booth designed to protect all other personnel from tiE glare and radiation. A chipping hammer for the removal of slag from the weld. A wire brush to clean the weld, and to remove spatter.

A steel bench insulated from the booth. A wooden duck board to safeguard the welder from damp floors. First set the control unit to the correct current specified for the size of electrode being used. The value recommended by the makers is only a mate; the final setting is made as the welding operation proceeds.

I electrode is then brought into contact with the plate by one of two me 1. The tapping-motion method as shown in Fig. The scratching method as shown in Fig. As in the previous method the el promptly raised a distance equal to its diameter, otherwise it will stick to the plate. If the electrode does stick the holder should be given a sharp twist; failing this the electrode should be released from holder, or the electric current should be switched off. Hand Protection Multi-use gloves shall be worn to protect the hands from injuries caused by handling sharp or jagged objects, wood, or similar hazard-producing materials.

Head Protection Hard hats shall be worn by all personnel working below other workers and in areas where sharp projections or other head hazards exist. Hearing Protection Appropriate hearing protection shall be used where employees are in designated hazardous noise areas with operating noise sources, or using tools or equipment which are labeled as hazardous noise producers.

Proper Lifting Techniques Before lifting, take a moment to think about what you're about to do. Examine the object for sharp corners, slippery spots or other potential hazards.

Know your limit and don't try to exceed it. Ask for help if needed, or if possible, divide the load to make it lighter. Know where you are going to set the item down and make sure it and your path are free of obstructions. Then follow these steps. Stand close to the load with your feet spread apart about shoulder width, with one foot slightly in front of the other for balance.

Squat down bending at the knees not your waist.

Tuck your chin while keeping your back as vertical as possible. Get a firm grasp of the object before beginning the lift. Begin slowly lifting with your LEGS by straightening them. Never twist your body during this step. Once the lift is complete, keep the object as close to the body as possible.

As the load's center of gravity moves away from the body, there is a dramatic increase in stress to the lumbar region of the back. Hand and Power Tools Tools are such a common part of our lives that it is difficult to remember that they may pose hazards. All tools are manufactured with safety in mind but, tragically, a serious accident often occurs before steps are taken to search out and avoid or eliminate tool-related hazards.

Hand Tools Hand tools are non-powered. They include anything from axes to wrenches. The greatest hazards posed by hand tools result from misuse and improper maintenance. Always think when using a tool: Every tool was designed to do a certain job.

Use it for its intended purpose. Keep them dressed sharpened to avoid flying spalls. Use tool holders. Never hold small work in your hand when using a screwdriver. Should not have broken claws or handles. Always use proper handles. Use the proper size and type of screwdriver for the job. Appropriate personal protective equipment, e. Power Tools Power tools can be extremely dangerous if they are used improperly. Each year, thousands of people are injured or killed by power tool accidents.

Common accidents associated with power tools include abrasions, cuts, lacerations, amputations, burns, electrocution, and broken bones. These accidents are often caused by the following: In additional to general shop guidelines, follow these guidelines for working with power tools: Do not use a tool or attachment for something it was not designed to do.

This precaution will reduce the chance for an accident and improve the quality of your work. Working too slowly can cause an accident just as easily as working too fast. Stop working if something distracts you.

Do not use your hand to clear jams or blockages, use an appropriate tool. Cover exposed belts, pulleys, gears, and shafts that could cause injury. WEEK 2: Belts, gears, shafts, pulleys, fly wheels, chains, and other moving parts must be guarded if there is a chance they could contact an employee. There are three types of barrier guards that protect people from moving machinery. They consist of the following: For example, portable circular saws must be equipped with guards.

An upper guard must cover the entire blade of the saw. A retractable lower guard must cover the teeth of the saw, except when it makes contact with the work material. The lower guard must automatically return to the covering position when the tool is withdrawn from the work.

Housekeeping Good housekeeping shall be maintained in all shops, yards, buildings, and mobile equipment. Supervisors are responsible for good housekeeping in or around the work they are supervising.

As a minimum, the following requirements shall be adhered to: Material shall not be placed where anyone might stumble over it, where it might fall on someone, or on or against any support unless the support can withstand the additional weight. Aisles and passageways shall be kept clear of tripping hazards. Nails shall be removed from loose lumber or the points turned down.

Mec 111 Total.pdf

Ice shall be removed from all walkways and work areas where it may create a hazard or interfere with work to be done. If ice cannot be removed readily, sand or other approved materials shall be applied. Trash and other waste materials shall be kept in approved receptacles. Trash shall not be allowed to accumulate and shall be removed and disposed of as soon as practicable, at least once per shift or more often if needed. Disconnect switches, distribution panels, or alarm supply boxes shall not be blocked by any obstruction which may prevent ready access.

Machinery and equipment shall be kept clean of excess grease and oil and operating conditions permitting free of excessive dust. Pressure gauges and visual displays shall be kept clean, visible, and serviceable at all times. Drip pans and wheeled or stationary containers shall be cleaned and emptied at the end of each shift.

Tutorial 1 1 Look at figure 1. Loose tools carried while mounting a ladder.

Badly arranged tools. Climbing up on unstable supports. Carrying things that limit the vision ahead. Throughing tools. Lift wood pieces with nails. Uncleaned workshop floor. Pointing compressed air on others. Broken bottles on the ground. Lift pipes in the middle of the workshop. Standing bellow lifted materials. Carrying long bars. Carrying heavy loads. Uncovered pits.

WEEK 4: Perform simple measuring exercise using steel rules, vernier calipers and micrometers. Use dial indicators to i set up jobs on the lathe ii Roundness testing etc 3.

Carry out exercise involving flatness squareness, straightness and surface finish test.

Prepare and mark out the sheet using steel rule and scriber as shown. Prepare and measure as shown. Set up the work piece on the vice Hold the sheet metal in a hand vice as shown. Marking out for Drilling operation Drills and drilling operation Drilling and reaming operation Speed and drills selection for drilling different materials WEEK 7: The type of datum depends on the part to be marked out and the material to be used.

Datum face: Used when marking out from face of the work piece. Datum edge: The edge of the work piece is used for measuring and marking out. Datum line: Used in sheet metal work when marking out irregular shape centre line. Datum point: The centre of the circle or round object is used for measuring and marking out.

Fig 4. Select correct tapping drill size. Select correct taps. Carry out tapping operation. Prepare a hole to the tapping drill size by drilling to the size of the hole. Place the work piece on the vice or position it on the lathe. Set the tap as shown. Fabricate metal container by knock-up joining 2. Join metals by the grooving technique. Carry out soft soldering. Oxyacetylene Welding Learning outcomes: Follow and recognize all safety methods and precautions when oxy-acetylene welding in the flat position.

Identify the equipments used in oxyacetylene welding.

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Carry out the oxy-acetylene welding of various joints in the flat position correctly. Safety Clothing The figure below show the welding safety clothing. Personal Protective Equipment: Protect your eyes with safety glasses. Proper Ventilation Be sure there is adequate ventilation available when welding in confined areas or where there are barriers to air movement. Natural drafts, fans and positioning of the head can help keep fumes away from the welder's face.

Week Running continuous weld bead with filler rod Objective -The student should be able to use the filler rod to produce continuous runs. Tools and materials - Oxy-acetylene welding station, filler rod, scriber, steel rule, carbon steel Procedures 1- Mark the layout as shown in fig a Fig a 2- Set the flame to neutral. Objective -The student should be able to use the filler rod to produce continuous runs.The a.

Select correct tapping drill size. WEEK 4 3. Protect hoses and cylinders from sparks, flames and hot metal. Datum face: Used when marking out from face of the work piece. Identify the equipments used in oxyacetylene welding. Care of dies Turning tool 3. Isosceles triangle: